From: sashiko-bot@kernel.org
To: "SJ Park" <sj@kernel.org>
Cc: damon@lists.linux.dev
Subject: Re: [PATCH 2/3] mm/damon/core: move static variable last_nr_regions to damon_ctx
Date: Sun, 25 Oct 2026 16:53:51 +0000 [thread overview]
Message-ID: <sashiko-outbox-184284@kernel.org> (raw)
In-Reply-To: <20261025164808.152048-3-sj@kernel.org>
> kdamond_split_regions() uses a static variable last_nr_regions, to infer
> if the region boundaries are too stable. If it looks too stable, it
> does a more aggressive region split because it might be a fake stability
> coming from non-aggressive split. Because the variable is static, the
> inference can be racy and wrong when multiple kdamonds are running in
> parallel.
>
> The user impact is not critical. No crash, no leak. DAMON's
> best-effort monitoring accuracy can be degraded when multiple kdamonds
> are used in parallel and the workload has certain access patterns. Still
> it is a bug that is better to fix.
>
> Move the variable into the damon_ctx struct to fix the problem.
>
> Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts")
> Cc: <stable@vger.kernel.org> # 5.15.x
> Closes: https://sashiko.dev/#/bug/linux-eebfcdde-2881-48ef-8df1-e2019d2a47f2
> Signed-off-by: SJ Park <sj@kernel.org>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261025164808.152048-1-sj@kernel.org?part=2
next prev parent reply other threads:[~2026-10-25 16:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-25 16:48 [PATCH 0/3] mm/damon: fix three race bugs in sysfs and core SJ Park
2026-10-25 16:48 ` [PATCH 1/3] mm/damon/sysfs-schemes: hold damon_sysfs_lock in target_metric_store() SJ Park
2026-10-25 16:52 ` sashiko-bot
2026-10-25 16:48 ` [PATCH 2/3] mm/damon/core: move static variable last_nr_regions to damon_ctx SJ Park
2026-10-25 16:53 ` sashiko-bot [this message]
2026-10-25 16:48 ` [PATCH 3/3] mm/damon/core: move static variable rotation " SJ Park
2026-10-25 16:51 ` sashiko-bot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=sashiko-outbox-184284@kernel.org \
--to=sashiko-bot@kernel.org \
--cc=damon@lists.linux.dev \
--cc=sashiko-reviews@lists.linux.dev \
--cc=sj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.